Attention is hereby directed to U.S. patent application Ser. No. 08/297,200 (D/94226) entitled xe2x80x9cPuzzle Cut Seamed Beltxe2x80x9d, now U.S. Pat. No. 5,514,436, issued May 7, 1996; U.S. patent application Ser. No. 08/297,158 (D/93563) entitled xe2x80x9cPuzzle Cut Seamed Belt With Strength Enhancing Stripxe2x80x9d, now continuing U.S. patent application Ser. No. 08/522,622, filed Aug. 31, 1995; U.S. patent application Ser. No. 08/297,201 (D/94225) entitled xe2x80x9cPuzzle Cut Seamed Belt With Bonding Between Adjacent Surface By UV Cured Adhesivexe2x80x9d, now U.S. Pat. No. 5,487,707, issued Jan. 30, 1996; U.S. patent application Ser. No. 08/297,206 (D/94226Q) entitled xe2x80x9cEndless Seamed Belt with Low Thickness Differential Between the Seam and the Rest of the Beltxe2x80x9d, allowed, but not yet issued; and U.S. patent application Ser. No. 08/297,203 (D/94227) entitled xe2x80x9cPuzzle Cut Seamed Belt with Bonding Between Adjacent Surfacesxe2x80x9d, all commonly assigned to the assignee of the present invention and filed on Aug. 29, 1994.
This invention relates generally to a process and apparatus for producing an endless seamed flexible belt, and more particularly concerns forming the ends of the flexible belt in a puzzle cut pattern which interlock to form a very low profile seam.
Initially, flexible belts were fabricated by taking two ends of a web material and fastening them together by a variety of techniques such as sewing, wiring, stapling, providing adhesive joints, etc. While such joined or seamed belts are suitable for many applications, such as the delivery of rotary motion from a source such as a motor, to implement a device such as a saw blade, they are not as satisfactory in many of the more sophisticated applications of belt technology in common practice today. In the technology of the current day, many applications of belts require much more sophisticated qualities and utilities, and in particular, for such special applications as in electrostatographic imaging apparatus and processes using a flexible photoreceptor belt or a flexible electroreceptor belt, in combination with either a intermediate transfer member, or image transport devices, or fusing member, or transfix devices in the flexible belt form. It is ideal to provide a seamless flexible belt whereby there is no seam in the belt which mechanically interferes with any operation that the belt performs or any operation that may be performed on the belt. While this is ideal, the manufacture of seamless belts requires rather sophisticated manufacturing processes which are expensive and are particularly more sophisticated, difficult and much more expensive for the larger belts. As a result, various attempts have been made to provide seamed belts which can be used in these processes. Previous attempts to manufacture seamed belts have largely relied on belts where the two opposite ends of a rectangularly cut sheet of the belt material have been lapped or overlapped and ultrasonically welded to form the seam, or have butted against one another and then fastened mechanically by heat or other means of adhesion such as by the use of an adhesive.
The belts formed according to the typical butting technique while satisfactory for many purposes are limited in bonding, strength and flexibility because of the limited contact area formed by merely butting the two ends of the belt material. Furthermore, belts formed according to the lapping or overlapping and ultrasonic welding technique have excessive seam thickness which provides a bump or other discontinuity in the belt surface leading to a significant height differential over the adjacent portions of the belt, of 0.003 inches or more depending on the belt thickness, which leads to performance failure in many applications. In electrostatographic imaging process utilizing an overlapping ultrasonically welded seamed belt, two most severe problems that the imaging belt has encountered during the imaging and cleaning processes are, for example, one involves cleaning the imaging belt of residual toner after transfer of the toner image due to the excess in seam height, while the other is the dynamic fatigue seam cracking as a result of large induced bending stress when seam bends and flexes over various belt support rollers of the belt module caused by the increase in seam thickness. Therefore, with a bump, crack or other discontinuity in the seam area of the belt, the cleaning function of a blade is affected which allows toner to pass under the blade and not be effectively cleaned off from the imaging belt surface, since intimate contact between the imaging belt and the cleaning blade is not maintained. A crack in the seam has also been seen to become a site that collects and traps toners which are eventually spewed out to the imaging zones of the imaging belt surface causing copy printout defects. Furthermore, seams having differential heights may, when subjected to repeated striking by cleaning blades, cause the untransferred, residual toner to be trapped in the irregular surface morphology of the seam. As a consequence, an electrostatographic imaging belt which is repeatedly subjected to this striking action, during imaging and cleaning processes, tends to delaminate at the seam when the seam is subjected to constant battering by the cleaning blade. Since the severe mechanical interaction between the cleaning blade and the seam also causes blade wear problem, the result often observed is that both the cleaning life of the blade and the overall life of the imaging belt under a service environment can be greatly diminished as well as degrading the copy print-out quality. In addition, the mechanical striking of the cleaning blade over the excessive seam height has also been found to give rise to vibrational disturbance in imaging development zone which affects the toner image formation on the belt and degrades resolution and transfer of the toner image to a receiving copy sheet. Moreover, the discontinuity or seam bump in such a belt may result in inaccurate image registration during development, inaccurate belt tracking and overall deterioration of motion quality, as a result of the translating vibrations. This is particularly prevalent in those applications requiring the application of multiple color layers of liquid or dry developer on an imaging belt surface to form the colored toner images, which are subsequently transferred to the final receiving copy sheet. Another disadvantage is that the presence of the discontinuity in belt thickness at the seam area has also been seen to reduce the flex life and continuity of strength of the belt during dynamic fatigue belt cycling when belt bends over various belt support module rollers.
Therefore, for all practical application purposes and prolonging a belt""s service life, it is desired to provide a seam height differential between the seam and the unseamed adjacent portions less than 0.001 inch or not to add more than 20 percent of the unseamed parent material thickening.
It has been shown that an endless seamed belt, having very small seam height differential, can be formed with patterned interlocked ends, the pattern of the ends being formed by using a laser or a die to cut the pattern and the patterned cut ends being brought together to interlock to form a seam. In experiments the patterned seams were first generated using a CO2 laser programmed to make various patterned node sizes and spacings. Although the laser was an excellent tool for providing the cut pattern geometries and conditions, however it was a costly and timely process and an inappropriate process for manufacturing seams for large volumes of belt production implementation because the focused CO2 laser has a fine beam size that has to make hundreds of bends, twists, and turns in order to produce the small node pattern cuts as the laser traverses across the whole wide of the imaging web. Since the CO2 laser is a heat laser, the generated heat that melts and cuts the imaging web material has been found to cause heat induced material shrinkage of the cut patterns. Alternatively, a 1 inch length punch press die was designed to cut small belt seam samples for testing purposes. The die cut is much faster and cleaner than the CO2 laser cut and the die cut was determined to be the preferred method to be used in the patterned seam belt manufacturing process; unfortunately, the mechanical force employed for cutting the imaging web is also seen to cause the material to develop permanent deformation. To yield the desirable seam cut pattern, the size of approximately 0.5mm and the spacings of approximately 25 microns for the nodes, it requires very accurate cutting by a die. Such a requirement has been found to be impossible for a die to maintain and provide the demanding tolerances for the width of an operational belt seam.
In essence, both the CO2 laser and mechanical die cutting methodologies have their respective undesirable shortcoming of causing imaging material dimensional change at the vicinity of the cut patterns, which have a precise shape tolerance to yield the perfect seam mating result. Therefore, there is an urgent need at present to develop a mechanically robust thin seam design and its preparation method for imaging belts application.
The following disclosures may be relevant to various aspects of the present invention:
U.S. Pat. No. 1,303,687
Inventor: C. Leffler
Issued: May 13, 1919
U.S. Pat. No. 2,461,859
Inventor: A. J. Vasselli
Issued: Feb. 15, 1949
U.S. Pat. No. 2,792,318
Inventor: H. P. Welch
Issued: May 14, 1957
U.S. Pat. No. 4,878,985
Inventor: Thomsen et al.
Issued: Nov. 7, 1989
U.S. Pat. No. 5,286,586
Inventor: Foley et al.
Issued: Feb. 15, 1994
U.S. Pat. No. 4,624,126
Inventor: Avila et al.
Issued: Nov. 25, 1986
U.S. Pat. No. 5,688,355
Inventor: Yu
Issued: Nov. 18, 1997
Some relevant portions of the foregoing disclosures may be briefly summarized as follows:
U.S. Pat. No. 1,303,687 teaches forming a container from a body blank with the ends dovetailed together and a covering sheet which extends beyond the end of the body and has its extending portion secured down, overlapping the dovetail joint to secure and finish the container. In forming the container, the body blank is wrapped around a forming mandrel of the desired shape and the two dovetail ends are interlocked. At the same time the extending ends of the covering sheet, which are provided with adhesive, are stuck down overlapping the joint.
U.S. Pat. No. 2,461,859 teaches an endless flexible belt with a patterned dovetail joint. A single die cut may cut both ends of the patterned dovetail joint at the same time. The ends of the belt are cut to form a male and female end with a plurality of spaced dovetailed tabs, the female end fitting into the male end and the dovetailed tabs interlocking with each other. An adhesive may be used at the belt joint.
U.S. Pat. No. 2,792,318 discloses forming splice joints in fibrous material, each joint being cut so that an interlocking tongue and groove pattern is formed. The tongues and grooves may be different shapes. In the finished product, the joints are oriented at a diagonal with respect to the sides. A coating material may be used to maintain the interfitted tongues and grooves, however, it is the interlocking connection of the tongues and grooves that provides the tensile strength of the joint.
U.S. Pat. Nos. 4,878,985 and 5,286,586 disclose fabricating thin flexible endless belts used in electrophotographic printing systems. The patents teach overlapping the ends of the belt and welding the ends together to form an endless belt.
U.S. Pat. No. 4,624,126 teaches a hydraulic press with a cylinder arrangement for equalizing forces in the event of unequal loading of the press.
U.S. Pat. No. 5,688,355 discloses fabricating a flexible belt by removing some of the layers on the belt ends by ablation with a masked excimer laser beam. The ends are overlapped to form a substantially thin flat surface and fused together to form the endless belt.
U.S. patent application Ser. No. 08/721,418 entitled xe2x80x9cProcess and Apparatus for Producing an endless Seamed Beltxe2x80x9d by Schlueter, Jr. et al., filed Sep. 26, 1996 and assigned to the same assignee as the present invention, teaches producing an endless flexible belt using a punch and die. The punch and die have patterned edges in the form of a puzzle cut pattern with extremely small nodes and kerfs. The cutting tolerances of the patterned edges make it necessary to fix the punch with respect to the die so that there is no misalignment of the punch and die between cutting operations.
All of the above references are herein incorporated by reference.
To overcome the above shortfalls and provide a mechanically robust thin seam design for flexible belt application, one aspect of the invention is drawn to a method for producing an endless flexible seamed belt from belt material stock including positioning a template above the belt material stock and applying a cutting force to the template to form a first patterned end and a second patterned end on the belt stock material. The cutting force is removed resulting the first and second patterned ends of the belt are cut in a puzzle cut pattern with mutually mating elements which fit together to form a seam when joined mechanically to enable the endless flexible seamed belt to essentially function as an endless belt having a substantially uniform thickness.
Another aspect of the invention is drawn to an apparatus for producing an endless flexible seamed belt from belt material stock including a template with a puzzle cut pattern formed thereon positioned above the belt material stock and a cutting force applied to the template to form a first patterned end and a second patterned end on the belt stock material, wherein the first and second patterned ends of the belt are cut in a puzzle cut pattern with mutually mating elements which fit together to form a seam. When the ends are joined mechanically a flexible seamed belt which essentially functions as an endless belt having a substantially uniform thickness is formed.
Yet another aspect of the invention is drawn to an endless flexible seamed belt made by an apparatus including a template with a puzzle cut pattern formed thereon positioned above the belt material stock and a cutting force applied to the template to form a first patterned end and a second patterned end on the belt stock material. The first and second patterned ends of the belt are cut in a puzzle cut pattern with mutually mating elements which fit together to form a seam when joined mechanically to enable the flexible seamed belt to essentially function as an endless belt having a substantially uniform thickness.
In a manufacturing mode, it is desirable to have a fast and accurate method of forming the puzzle cut seam design. Using a template having the desired puzzle-cut pattern in combination with an excimer laser for cutting the flexible belt material and creating the pattern is much quicker and cleaner without the heat induced material deformation problem as that seen associated with using a CO2 laser to form the puzzle cut seam. Alternatively, a template in the form of a punch and die is also a quick and clean way to cut the flexible belt material. Employing the excimer laser cutting and punch and die cutting are cleaner than the laser cut due to the fact that the CO2 laser melts the belt material, which is a particular problem in a multi-layered belt. Having a clean and low profile puzzle cut seam pattern is very important when the belt is used in an electrophotographic machine environment due to the stringent requirement of very small distances existing between the electrophotographic process subsystem elements and the belt surface.